CVE-2025-6021
📋 TL;DR
This CVE describes an integer overflow vulnerability in libxml2's xmlBuildQName function that can cause stack-based buffer overflow when processing malicious XML input. This vulnerability affects any system or application that uses libxml2 to parse XML documents, potentially leading to memory corruption or denial of service. The flaw is particularly concerning for web servers, XML processing tools, and applications that handle untrusted XML input.
💻 Affected Systems
- libxml2
- Applications using libxml2 library
📦 What is this software?
Enterprise Linux For Ibm Z Systems by Redhat
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Enterprise Linux For Ibm Z Systems by Redhat
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Enterprise Linux For Ibm Z Systems by Redhat
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Enterprise Linux For Ibm Z Systems Eus by Redhat
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Enterprise Linux For Ibm Z Systems Eus by Redhat
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Enterprise Linux For Ibm Z Systems Eus by Redhat
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Enterprise Linux For Ibm Z Systems Eus by Redhat
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Enterprise Linux For Power Little Endian by Redhat
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Enterprise Linux For Power Little Endian by Redhat
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Enterprise Linux For Power Little Endian by Redhat
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Enterprise Linux For Power Little Endian Eus by Redhat
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Enterprise Linux For Power Little Endian Eus by Redhat
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Libxml2 by Xmlsoft
Openshift Container Platform For Arm64 by Redhat
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Openshift Container Platform For Ibm Z by Redhat
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Openshift Container Platform For Ibm Z by Redhat
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Openshift Container Platform For Ibm Z by Redhat
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Openshift Container Platform For Ibm Z by Redhat
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Openshift Container Platform For Linuxone by Redhat
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⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise if an attacker can control the overflow to execute arbitrary code.
Likely Case
Denial of service through application crashes or memory corruption disrupting XML processing functionality.
If Mitigated
Limited impact with proper input validation and memory protection mechanisms in place.
🎯 Exploit Status
Exploitation requires crafting specific XML input to trigger the integer overflow and subsequent buffer overflow.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: libxml2 2.11.8 or later
Vendor Advisory: https://access.redhat.com/errata/RHSA-2025:10630
Restart Required: Yes
Instructions:
1. Update libxml2 package using system package manager. 2. For Red Hat systems: yum update libxml2. 3. Rebuild or restart applications using libxml2. 4. Verify the update with version check.
🔧 Temporary Workarounds
Input Validation
allImplement strict XML input validation and sanitization before processing.
Memory Protection
linuxEnable ASLR and stack protection mechanisms at OS level.
sysctl -w kernel.randomize_va_space=2
🧯 If You Can't Patch
- Implement network segmentation to isolate XML processing systems
- Deploy web application firewall with XML payload inspection
🔍 How to Verify
Check if Vulnerable:
Check libxml2 version: xml2-config --version or rpm -q libxml2Check Version:
xml2-config --version || rpm -q libxml2 || dpkg -l libxml2Verify Fix Applied:
Verify version is 2.11.8 or higher and test XML processing functionality📡 Detection & Monitoring
Log Indicators:
- Application crashes related to XML parsing
- Memory corruption errors in system logs
- Unusual XML processing patterns
Network Indicators:
- Malformed XML payloads in network traffic
- XML documents with unusually large element names
SIEM Query:
source="application_logs" AND ("segmentation fault" OR "buffer overflow" OR "xml parsing error")🔗 References
- https://access.redhat.com/errata/RHSA-2025:10630
- https://access.redhat.com/errata/RHSA-2025:10698
- https://access.redhat.com/errata/RHSA-2025:10699
- https://access.redhat.com/errata/RHSA-2025:11580
- https://access.redhat.com/errata/RHSA-2025:11673
- https://access.redhat.com/errata/RHSA-2025:12098
- https://access.redhat.com/errata/RHSA-2025:12099
- https://access.redhat.com/errata/RHSA-2025:12199
- https://access.redhat.com/errata/RHSA-2025:12237
- https://access.redhat.com/errata/RHSA-2025:12239
- https://access.redhat.com/errata/RHSA-2025:12240
- https://access.redhat.com/errata/RHSA-2025:12241
- https://access.redhat.com/errata/RHSA-2025:13267
- https://access.redhat.com/errata/RHSA-2025:13289
- https://access.redhat.com/errata/RHSA-2025:13325
- https://access.redhat.com/errata/RHSA-2025:13335
- https://access.redhat.com/errata/RHSA-2025:13336
- https://access.redhat.com/errata/RHSA-2025:14059
- https://access.redhat.com/errata/RHSA-2025:14396
- https://access.redhat.com/errata/RHSA-2025:15308
- https://access.redhat.com/errata/RHSA-2025:15672
- https://access.redhat.com/errata/RHSA-2025:19020
- https://access.redhat.com/security/cve/CVE-2025-6021
- https://bugzilla.redhat.com/show_bug.cgi?id=2372406
- https://lists.debian.org/debian-lts-announce/2025/07/msg00014.html
- https://gitlab.gnome.org/GNOME/libxml2/-/issues/926
